Global to Local modelling and forecasting Deltares provides several global hydrodynamic models and forecasting systems to generate boundary conditions and forecasts for local scale models. The key models and systems mentioned are the Global Tide and Surge Model (GTSM), the Global Storm Surge Information System (GLOSSIS), and the Blue Earth Data platform. GTSM is a depth-averaged hydrodynamic model with 2.5km resolution that can provide boundary conditions and forecasts. GLOSSIS runs GTSM in forecast mode out to 10 days to provide global water level forecasts. Blue Earth Data serves as a platform for sharing modeling results. The presentation discusses using these systems to enable multi-hazard forecasting from global to local scales.

1. Kun Yan, Sanne Muis, Martin Verlaan, Jelmer Veenstra, Julien Groenenboom, and many
other colleagues
Deltares global models, systems and services
2023-02-22
Global to Local modelling
and forecasting

2. A Deltares Global Model
2
Global Tide and Surge Model
• Depth-averaged hydrodynamic model
• Delft3D FM Suite with D-Flow FM module
• 2.5 km (1.25 in Europe) resolution at the coast
Applications
• Metocean & boundary conditions for local
models
• Operational forecasting
• Reanalysis of historical extremes
• Future climate projections
GTSM wiki:
https://publicwiki.deltares.nl/display/GTSM/
Global+Tide+and+Surge+Model
GTSM model unstructured grid in South East Asia
DSD-SEA
2023
Global
to
local
multi-hazard
forecasting

3. • Global 2D barotropic model, no (lateral) boundary conditions
• Unstructured global grid refined based on improved bathymetry
• Resolution 25 km ocean - 2.5km coastal/1.25km EU, up to 800m
• Bathymetry: GEBCO2021 and EMODNET2018 bathymetry with LAT correction
(in GTSMv5)
• Process:
• Tidal forcing
• Bottom friction dissipation
• Self Attraction and Loading (SAL)
• Internal tide friction dissipation
• Simulation speed
• 2.1 hours for 10 day simulation on 16 cores (2x8 normal-e3-c7 nodes)
• Pretty good global and local statistics (and improving)
Global Tide and Surge Model v4
GTSM model validation (upper panel)
GTSM model grid in South East Asia (left) and Europe (right)

4. Global Storm Surge Information System
GLOSSIS = Global Tide and Surge Model running in forecast mode from a
Delft-FEWS forecasting engine
• New forecast 7d-10d lead time every 6 hrs
• Based on wind and msl pressure forecasts from NOAA GFS
• Output: water level, tide, storm surge, depth averaged currents (maps and
time series) for the entire world
• Hosted at Deltares (private cloud) with production and testing systems
GLOSSIS forecast vs observed time series of tide, surge, water level
GLOSSIS water level forecast in the FEWS GUI
GLOSSIS output locations in the FEWS GUI

5. Blue Earth Data
5
https://blueearthdata.org/data
DSD-SEA
2023
Global
to
local
multi-hazard
forecasting

6. Blue Earth Data
Currently: multi-data viewer
Outlook: multi-data platform
1. Workbench for expert users
− Online analysis with STAC datasets (interoperable)
− GitHub repository with examples
2. Download for non-expert users
− Offline analysis with own on-premise datasets
− Plug into in-house models / tools
3. Scheduler for boundary conditions
− Feed into early warming forecasting system (FEWS)
4. OGC web service (WMS, WFS)
− Host datasets on your own maps / viewers
https://blueearthdata.org/data
By BlueEarthData Team Deltares, Etiënne Kras

7. GLOSSIS Data Service
7
Forecast provisioning to
MadeSmart Group
(“MSG RealTide”)
Showcasing in iD-Lab
NRT hindcast provisioning
to SEADRIF re-insurance
platform
Forecast provisioning
to FEWS-INAM
(Mozambique)
Sharing results through
BlueEarth Data
DSD-SEA
2023
Global
to
local
multi-hazard
forecasting

8. Forecast Floats in Turbulence Challenge
8
DSD-SEA
2023
Global
to
local
multi-hazard
forecasting

9. Global extreme sea level multi-model projections
• Global sea level dataset for 1950 to 2050 with reanalysis and climate projections (RCP8.5)
• 5 high-resolution climate models from the HighResMIP (CMIP6) experiment with SLR
• Advanced extreme values statistics including changes, ensemble statistics
• Publicly available at the Copernicus Climate Data Store (CDS) since Dec 2021
10
DSD-SEA
2023
Global
to
local
multi-hazard
forecasting

10. Methodology
11
DSD-SEA
2023
Global
to
local
multi-hazard
forecasting

11. Global changes of Tide due to SLR
12
Change of global tide (MHHW, Mean High High Water, 95 prct) in 2100 under RCP8.5 scenario
DSD-SEA
2023
Global
to
local
multi-hazard
forecasting

12. Global changes of surge level
• SLR + wind + pressure
• 1-in-10 year
• 2021-2050 against 1951-1980
13
Change (%)
Change (m)
Change of surge (1-in-10 year) under RCP8.5 scenario (Muis et al., submitted)
DSD-SEA
2023
Global
to
local
multi-hazard
forecasting

13. Global Flood Map: Microsoft PC
• High resolution (90m) (coastal) global flood mapping from 2018 to 2050 based
on global DEMs and extreme sea level data
• (coastal) global flood mapping based on LiDAR DTM (5km spatial resolution)
• A global coastal event catalogue (Tropical Cyclone induced)
• Understanding of change in coastal flood inundation under Sea Level Rise
(SLR)
• Data produced in Microsoft Azure, publicly available on Microsoft Planetary
Computer
• https://github.com/microsoft/AIforEarthDatasets#deltares-global-flood-maps
DEM Resolution Original datum
Return period
(yr)
Periods
Number of
runs
MERIT 1km, 90m EGM96
0, 2, 5, 10, 25, 50,
100, 250
2018 (Present day )/
2050 (+ SLR)
32
NASA 1km, 90m EGM96
0, 2, 5, 10, 25, 50,
100, 250
2018 (Present day )/
2050 (+ SLR)
32
LIDAR 5km MSL
0, 2, 5, 10, 25, 50,
100, 250
2018 (Present day )/
2050 (+ SLR)
16
Global flood map simulations in GFM Microsoft project
Inundation depth and extent in the Netherlands with the MERIT DEM at a 90m
resolution (for different return periods, for both the present-day sea level and the
2050 sea level rise projection)
Microsoft Planetary Computer

14. Global to local forecasting: Vision
• WMO/UN: Early warning systems must protect everywhere within five years (2022)
• Deltares Moonshot: Hundreds of millions of people will be better protected from floods at an
acceptable cost by 2030
• Vision: Provide locally relevant multi-hazard forecast with a global scale, by an open API as
data service, with response time no more than few hours.
• We need:
− Robust forecasting system
− (coupled) Multi-hazard global models
− Model builder
− Cloud-native solutions
− Open API
15
→ Delft-FEWS and Cloud
→ GTSM, wflow_sbm, Global ground water model
→ Hydromt, downscaling toolkit
→ Docker, Kubernetes, HPC
→ BlueEarthData, FEWS Web Service/Web OC, Deltares
Open Archive
DSD-SEA
2023
Global
to
local
multi-hazard
forecasting

15. Future-proof forecasting
• From Global coverage to
‘local relevance’
• Future-proof forecasting
service
− Easy to use (several
clicks)
− Fast (automation)
− Flexible /
interoperable (model
builder)
− Scalable (cloud-native)
16

16. Deltares Hackathon
17
DSD-SEA
2023
Global
to
local
multi-hazard
forecasting

17. Thanks for your attention!
www.deltares.nl
Kun.Yan@deltares.nl
@deltares
@deltares
linkedin.com/company/deltares
facebook.com/deltaresNL